IGF2 and Silver-Russell syndrome: These included the IGF2-KCNQ1 (BWS/SRS locus, chromosome 11p15.5), SNRPN (Prader-Willi Angelman (PWS-AS) locus, chromosome 15q11-q13), and DLK1-DIO3 (chromosome 14q32.2) loci (Fig. 1).